Purification of 6-{8 d-{60 -(3-guanyl-1-ureido)phenylacetamido{9 {0 penicillanic acid

ABSTRACT

6-(D- Alpha -(3-Guanyl-1-ureido)phenylacetamido)penicillanic acid is purified by reaction with nitric acid to form its crystalline nitrate (as a monohydrate) which in turn is converted by reaction with a base to the crystalline zwitterion hemihydrate. The last named is converted to its crystalline potassium salt (dihydrate) and to its crystalline sodium salt (monohydrate).

United States Patent 91 Kaplan et al. ['45] ,Jan. 16, 197;;

[54] PURIFICATION OF 6-[D-a-(3 -GUANYL- [56] References Cited l-UREIDO)PHENYLACETAMIDO] I v PENICILLANIC ACID I y UNITED STATES PATENTS [75] Inventors: Murray A. Kaphn Syracuse; 3,579,501 5/l97l McGrcgor ..260/239.|

Alphonse Peter Granatek, Baldwin- Svme both f Primary Exammer N|cholas S. Rlzzo V m H m WW WV I 1 Attorney-Herbert W. .Taylor, J Jr., Robert E. [73] 'fi BristoLMyer Company, e York, l-lavranek, Richard H. Brink and James Magee, Jr.

NY. 1 22 Filed: Feb. 3, 1971 7 a MTSTRACT 6-[D-a-(3-Guanyl-l ureido)phenylacetamidolpenicil [21] Appl' u2452 lanic acid is purified by reaction with nitric acid to form its crystalline nitrate (as a monohydrate) which LS-Cl. ..26 0/239.1, 424/271 in tum is converted by reaction with a base tqthe Int Cl. .Q. "C076 rystalline zwitter ion hemihydrate The named is converted to its crystalline potassium salt (dihydr'ate) Field of Search ..260/239.l

and to its crystalline sodium salt (monohydrate).

4 Claims, No Drawings UREIDO)PHENYLACETAMIDO PENICILLANIC ACID BACKGROUND OF THE INVENTION 1. Field of the invention The penicillins of the present invention possess the usual attributes of such compounds and are particularly useful in the treatment of Pseudomonas infections.

2. Description of the Prior Art g The preparation and properties of 6-[D-B-(3-guanyll-ureido )phenylacetamido]-penicillanic acid and its salts have been described by my colleague, Donald Neil McGregor, in U.S. Pat. applications Ser. No. 780,557, filed Dec. 2, 1968 and now abandoned and Ser. No. 852,457, filed Aug. 22, 1969, now U.S. Pat. No. 3,579,501, and also described in Belgium Pat. 742,423 (Farmdoc 39,705R) to Bristol-Myers Co.

This compound has the structure SUMMARY OF THE INVENTION Thepresent invention provides crystalline 6-[D-a- (3-guanyl-l-ureido)phenylacetamido]-penicillanic acid nitrate monohydrate, crystalline 6[D-a-(3-guanyll-ureido)phenylacetamidoj-penicillanic acid hemihydrate, crystalline potassium 6-[D-a-(3-guanyll-ureido)phenylacetamidol-penicillanate dihydrate and crystalline sodium 6-[D-a-(3-guanyll uredido)phenylacetamidol-penicillanate monohydrate.

- ureido)phenylacetamidolpenicillanic acid which com- 6-[D-cz-(3-guanyl-lprises converting crystalline ureido)-phenylacetamido]penicillanic acid nitrate monohydrate to highly purified-crystalline 6-[D-a-(3- guanyl-l-ureido)phenylacetamido]penicillanic' acid hemihydrate by slurrying it in 50 percent (v/v) aqueous isopropyl alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6-[D-a-( 3guanyl-l-ureido)phenylacetamido]-penicillanic acid hemihydrate spontaneously soon precipitates and is then collected.

The present invention also provides the process of purifying impure, amorphous 6-[D-a-(3-guanyl-lureido)phenylacetamido]-penicillanic acid which comprises mixing it with nitric acid in aqueous alcohol at a pH in the range of l to 2, recovering the crystalline 6- [D-a-( 3-guanyll -ureido )phenylacetamido]-penicillanic acid nitrate thus precipitated and then converting said nitrate to highly purified crystalline 6-[D-a-(3- guanyl-l-ureido)- phenylacetamido]penicillanic acid by slurrying it in aqueous alcohol and then adjusting the pHof said slurry with a base to the range of 4.5 to

6.0 to give a solution from whichthe purified crystal- 1 .6-[D-a-(3-guanyl-1-ureido)phenylacetamido] line penicillanic acid spontaneously soon precipitates and is then collected; and as a preferred embodiment, the process for purifying impure, amorphous 6-[D-a-(3- guanyll -ureido )phenylacetamido] penicillanic acid which comprises mixing it with nitric acid in 90 percent (v/v) aqueous isopropyl alcohol at a pH in the range of 1.3 to 1.9, recovering the crystalline 6-[D-a-(3-guanyl- 1-ureido)phenylacetamidolpenicillanic acid nitrate monohydrate thus precipitated and then converting said nitrate to highly purified crystalline 6-[D-a-(3- guanyll -ureido )phenylacetamido]-penicillanic hemihydrate by slurrying it in 50 percent (v/v) aqueous isopropyl alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6-[D-a-(3- guanyll -ureido )phenylacetamidojpenicillanic acid hemihydrate spontaneously soon precipitates and is then collected.

DETAILED DESCRIPTION centrated sulfuric acid and 40 ml. of concentrated nitric acid was added (caution!),.in small portions over 40 min., 25 g. (0.3 mole) of cyanoguanidine Eastman. After the addition was complete,'the reaction mixture was kept at about 0 for 1.5 hrs. with occasional swirling, then was poured into 1,000 g. of ice. The precipitate was removed by filtration and washed with water. Without drying, the precipitate was suspended in 200 ml. of water and dissolved by the addition of 10 percent aqueous NaOH The resulting solution was filtered, then the product was precipitated by bubbling.

CO, through'the solution for 1 hour. The solid was removed by filtration, washed with R 0, and dried, yielding 38.6 g. (88 percent), m.p. 250 Anal. Calcd. for C,H,N O C, 16.3; H, 3.43; N, 47.96.

Found C, 16.63; H, 3,65; N, 47.6. 4-Gu anylsemicarbazide dihydrochloride (11) A suspension of 5.88 g. (0.04 mole) of N-guanyl-N'- nitrourea in 31.8 ml. of concentrated HCl'was cooled by the addition of about 15 g. of ice and storage in an ice bath. The suspension was added over 45 min. to a vigorously stirred, ice-cooled mixture of 12.96 g. (0.18 mole) of zinc dust and about 300 g. of ice. After the addition was completed, the mixture was stored for 10 min. without external cooling and then, was filtered. The filtrate was shaken vigorously with 5 ml. (0.05 mole) of benzaldehyde, and the colorless precipitate which separated was quickly removed by filtration and benzal derivative of 11, m.p. 237.

acid

Without purification, 3.5 g. of the benzal derivative was suspended in ml. of ethanol, then 50 ml. of concentrated l-ICl was added and the mixture was stored at 40 for 1hr. The insoluble crystalline product was collected by filtration and recrystallized from waterethanol, yielding 1.0 g. of II, m.p. 191. 6-[ D( -a-( 3-Guanyl-1 -ureido )-phenylacetamido 1- penicillanic acid I To a stirred, ice-salt cooled solution of 1.0 g. (5.25 mmoles) of 4-guany1semicarbazide dihydrochloride in 6 ml. of B50 was added a solution of 0.366 g. (5.25 mmoles) of NaNO in. 1 .4 ml. of H 0. Stirring and cooling was continued for min. This solution of guanylcarbamoylatingagent prepared in situ was then added to a stirred, ice-cooled solution of 2.12 g. (5.25 mmoles) of ampicillin trihydrate in 7 ml. of H,O containing sufficient triethylamine to bring the pH to 7.5. After the solutions were combined, the pH was adjusted to 7.2 with triethylamine, and stirring and cooling was continued for 45 min. The precipitate which separated wascollected by filtration, washed with H 0, and dried, yielding 1.2 g. solid 6-[D-a-(3-Guanyl-1- ureido)-phenylacetamido]-penicillanic acid. This was reprecipitated twice by dissolving in 10 ml. of H 0 with triethylamine at pH 9.5, then acidifying of pH 5 (acidification to pH 6.5 is sufficient) with 42 percent H PO yielding 0.425 g. of 6-[D-a-(3-guanyl-lureido)-pheny1acetamido]-penici1lanic acid, m.p. l98l4 200 C.'Dec. Anal. Calcd. for C, I-I, N,O,S'I-l, O: C, 45.95; H, 5.57; N, 17.86.

Found:C,46.65;H,5.67;N, 17.51. This material was amorphous and, as will'be apparent from the Examples below, was also impure. High purityv and crystallinity are highly desirable, if not essential, attributes :of commercial penicillins and it was an object of the present inventionto provide 6-[D- a-(3-guanyl-1-ureido)phenylacetamido]-penicillanic acid and its sodium and potassium salts in such purity and to provide the necessary processes. It was discovered, according to the present invention, that impure, amorphous 6-[D-a-(3-guanyl-1- ureido)phenylacetamido]-penicillanic acid is converted to a highly purified nitrate salt or adduct by crystallization from 90 percent V/V isopropanol-water at pH 1-2.0. The nitrate in turn is converted to very pure free acid (zwitterion) by crystallization from 50 percent V/V isopropanol-water at pH 46.0. Thus crude amorphous 6-[D-a-(3-guanyl-1-ureido)-phenylacetamido]-penicillanic acid was converted to its purified crystalline nitrate salt in about 75 percent bioyield. The nitrate was converted to the pure (or nearly 7 pure) crystalline zwitterion in about an 86 percent step yield. A change in bio-potency of from 900 to 1,250

' hours at room temperature. Concentrated water solutions (250 m g./ml.) have a pH of 9.8'- 9.9 and are stable within =10 percentfor-at least 1 hour at room temphenylacetamido]-penicil-' perature. This salt is also readily soluble at 500 mg./ml.

in water (pH 9.9). Thu's a crystalline and highly u-.

rified potassium 6-[D-a-(3-guany1-1-ureido)phenylacetamidol-penicillanate dihydrate was prepared in good yield by a water-KOH-acetone or a water-KPH- TEAacetone procedure from crystalline free acid" 6- [D-a-(3-guanyl-1-ureido)phenylacetamido]-penici1- lanic acid hemihydrate. The biological stability of this potassium salt in water is about equal to or equivalent to that of corresponding aqueous solutions of potassium ampicillin.

It was further discovered, according to the present invention, that crystalline purified 6-{D-a-(3-guanyi-1- ureido)-phenylacetamido]penicillanic acid hemihydrate (zwitterion) is converted to crystalline sodium 6-[ D-a-( 3-guany1-1 -ureido )phenylacetamido] pen'icillanate monohydrate from acetone. This salt is very soluble in water. Dilute aqueous solutions (10 mgJmI.) exhibit a pH of 8.3 and are stable within 10 percent for at least 24 hours at room temperature. Concentrated aqueous solutions (250 mg./ml.) exhibit a pH of 9.8 9.9 and are stable within 10 percent for at least 2 hours at room temperature. This salt is also readily soluble at 500 mg./ml. (pl-19.9). Thus, a-crystalline and highly purified sodium 6-{ D-a-( 3 -guanyl'1- ureido)phenylacetamido]-penicillanate monohydrate is prepared in good yield by an acetone-water-SEH- TEA procedure from crystalline 6-[D-a-(3-guanyl-l DESCRIPTION OF THE PREFERRED EMBODIMENTS Crystallization of 6-[D'-a-(3-guany1-1-ureido)ph'en yl-acetamido]-penicillanic acid Nitrate Ten grams of amorphous, impure 6-{D-oz-(3-guanyl-' l-ureido)-pheny1acetamido]-penicillanic acid (100 mesh) was slurried in -100 ml. of 90 percent (V/ V) isopropanol-water; 1 3/10 ml. of concentrated nitric acid (or the volume of I-INO required to give a pH of 1.3-1.9) was added with very rapid stirring.'A solution (pl-I 1.3-1.9) or near solution was obtained. Crystallization started after seeding in 3 to 5 minutes. The mixture was slurried at ambient room temperature (21-24 C. for l-l.5 hours. The small needle crystals were collected by filtration, washed with 20 m1. of 90 percent isopropanol and then 30 ml. of isopropanol and then vacuum dried over P 0, at 50 C. for 24 hours. Yield: 6 grams of 6-[D-a-(3-guany1-1-ureido)phenylacetamidol-penicillanic acid nitrate monohydrate which was shown to be crystalline by the fact that it. exhibited extinction under the polarizing microscope. Comparison of this product with starting material gave the following results:

RESULTS starting material Product (crude (crystalline nitrate amorphous) monohydrate) Estimated Ampicillin 540% 0.1%

. %NO, (theory 12.5%)

-- 11S (theory 6.42%)

Content Bio-Assay 870-920 u/mgrn. 1,000 -1,050 u/mgm.

Chemical Assay in 590-630 u/mgm. 700-740 u/mgm.

Ampicillin Units Bio-Yield 60-76% [a1,,;DMAC +1 17, +144 +180 kl-1,0, KF (theoryfor 5.18% 2.7%

monohydrate 3.5%)

on dry'basis 12.2% %N (theory 19.7%

on dry basis 6.0% M P (Capillary) 205-209 C. (d)

Using as the standard a certain lot of crude 6-[D-d-(3-guanyl-lureido)phenylacetamidol-penicillanic acid which in this particular assay is about one-fourth as active as ampicillin.

EXAMPLE 2 Crystallization of 6-[D-a-(3-guanyl-1-ureido)phenylacetamidol-penicillanic acid hemihydrate-(zwitterion or free acid).

15 grams of crystalline 6-[D-a-(3-guanyl-l-ureido)- phenylacetamidol-penicillanic acid nitrate (100 mesh) was slurried in 100-150 ml. of 50 percent (V/V) isopropanol-water for 5 minutes. 20-40 percent sodium hydroxide (may be replaced by triethylamine) was added with very rapid stirring to a pH of 4.5-6.0. A solution was obtained. (A10 minute period of fast paper-gravity only filtration may be used if desired.) The mixture was seeded and crystallization started in about 15-20 minutes. The mixture was stirred at ambient room temperature (21-24 C.) for 2 hours. The small rod-like crystals were collected by filtration,

washed with 25 ml. of 50 percent isopropanol, thenwith 30 ml. of isopropanol and then vacuum dried over P at 50 C. for 24 hours. Yield: 11.5 grams of ,6-["D- a-(S-guanyl-1-ureido)phenylacetamidolpenicillanic acid hemihydrate which was shown to be crystalline by the fact that it exhibited extinction under the polarizing microscope. This product was analyzed with the following results: I

EXAMPLE 3 grams of 60 mesh crystalline purified 6-[D-a-(3- guanyl-l ureido)phenylacetamido]-penicillanic acid hemihydrate prepared according to Example 2 is slurried in a mixture of 10 ml. of water and 50 ml. of acetone. To this suspension is added 4.3 ml. of a 30 percent aqueous solution of potassium hydroxide with rapid stirring. A solution is obtained. (This solution does not crystallize and may be sterilely filtered through suitable filtersat positive pressure to remove bacteria and pyrogens. Filtration at this step, if desired, should be completed within 1 hour.) To this solution, 100 ml. of acetone is added over a 3 minute period with on dry basis= 19.3%

rapid stirring. The solution is seeded and crystallization starts in about 3 minutes. The mixture is slurried for l5- minutes. An additional 100 ml. of acetone is added over a three minute period and the mixture is slurried for one hour at ambient room temperature (21-14" C.). The small, thin, needle-like crystals which form are collected by filtration, washed with 65 ml. of acetone and air dried at 37-45 C. for 24 hoursfYield: 10 grams of potassium 6-[D-a(3-guanyl-1-uriedo)phenylacetamido]penicillanate dihydrate which was shown to be crystalline by the fact that it exhibited extinction under the polarizing microscope. This product was analyzed with the following results:

RESULTS Bio-Assay as in Example 1 1,100 1,180 units/mgm. Chemical Assay (as Ampicillin) 750 unitslmgm. Bio-Yield 95 percent Estimated Ampicillin content= 0.l percent Percent Water, K.F. 36* when dried in vacuo over P 0 at RT;

7.1" when air dried at 37-56; 9.02percent (after exposure to laboratory air for 24-48 hours)*** I Percent Ash as K (dry basis) 7.6 -8.2 (theoryf= 8.25 percent) PercentN (dry basis) 17.9 (theory 17.8 percent) S (dry basis) 6.85 (theory 6.77 percent) [a] ;DMAC=+164;3

IR and NMR gave spectra consistent with structure; no free or combined acetone.

EXAMPLE 4 10 grams of 100 mesh crystalline, purified 6-[D-a- (3-guanyl-1-ureido)phenylacetamido]penicillanic acid hemihydrate was slurried in 100 ml. of acetone Twenty-five ml. of a 28-30 percent solution of potassium 2- ethylhexanoate in methyl isobutyl kctone (KFH- MlBK) was added with rapid stirring. A near solution or solution was obtained in about three minutes. 2 ml. of water was added and a clear solution was obtained in about three minutes (This solution does not crystallize and may be sterilely filtered through suitable filters at positive pressure to remove bacteria and pyrogens. Filtration at this step if desired should be completed within one hour.) 3 (or up to 5) ml. of triethylamine (TEA) was added and the solution was seeded. Crystallization started in about 5-10 minutes. The mixture was slurried at ambient room temperature for 1 hour. The

crystals were collected by filtration, washed with ml.

of acetone and air dried at 37-45 C. for 24 hours. Yield: 7.0 grams of potassium 6-[ D-a-(3-guanyl-1- ureido)phenylacetamido]-penicillanate dihydrate which was shown to be crystalline by the fact that it exhibited extinction under the polarizing microscope. This product on analysis gave the following results:

RESULTS Bio-Assay as in Example 1 1,100 1,180 units/mgm.

Chemical Assay (as Ampicillin) 750 790 units/mgm. Bio-Yield percent Estimated Ampicillin Content O.l percent Percent Water, K.F. 7.2

Percent Ash as K (dry basis) 7.9 8.1 (theory 8.25

percent) Percent N (dry basis) 18.0 (theory 17.8 percent) Percent S (dry basis) 6.83 (theory 6.78 percent) Mk DMAC =+l69.4 IRand'NMR gave spectra consistent with structure; no free or combined acetone.

EXAMPLE 5 gramsof 60 mesh crystalline purified 6-[D-a-(3- guan yl- 1 -ureido)pheny1acetamido penicillanic acid hemihydrate (zwitterion) prepared according to Exampie 2 is slurried in 100 ml. of acetone at ambient room temperature (21-24 C.). 25 m1. of 28-30% solution of sodium 2-ethylhexanoate in methyl isobutyl keystone (SEI-I-MIBK) is added with rapid stirring. The mixture is slurried for 2 minutes. 5 ml. of water is added and a solution is obtained in about 1 minute. (This solution does not crystallize and may be sterilely filtered at positive pressure through suitable filters to remove particulate matter, bacteria and pyrogens. Filtration at this step if required should be completed within 1.5 hours). 3 (or up to 4) ml. of triethylamine (TEA) is added with rapid stirring. The solution is seeded and crystallization starts in about 3-5 minutes. The mixtureis slurried for -20 minutes to afford a heavy growth of crystals. 100 ml. of acetone is then added over a 10 minute period with very rapid stirring. The mixture is slurried for 30-45 minutes. The dense microcrystals are removed by filtration, washed with 65 ml. of acetone and air dried at 45 C. for 18-24 hours. Yield: 78.5 grams of sodium 6-[ D-a-(3-guanyl-1-uriedo)phenylacetamido] penicillanate monohydrate which was shown to be crystalline by the fact that it exhibited extinction under the polarizing microscope. This product on analysis gave the following results:

RESULTS Bio-Assay as in Example 1 1,120 1,220 units/mgm. Bio-Yield 70 85 percent I Chemical Assay (asampicillin) 790 830 units/mgm. Estimated Ampicillin Content= 0.1 percent Percent Water, KF 3.7 3.9 (*Theory for monohydrate 3.82 percent. This hydrate does not appear to be hydroscope and does not pick up a significant amount of water when exposed to laboratory air for 48 hours.)

Percent Ash as Na (dry basis) 4.5 4.85 (Theory 5.04 percent) Percent N (dry basis) cent) Percent S (dry basis) 7.2 1 7.6 (Theory 7.03' percent) M.P.(l0C./min.)=218220C. (d) IR-and NMR gave spectra consistent with structure; n free or combined acetone present.

FORMULATIONS Sodium 6-[D-04-(3-guanyl-l ureido)phenylacetamidolpenicillanate Monohydrate Solution For Parenteral Use (Equivalent to 250 mg./ml. of Anhydrous 6-[D-a-(3-g uany1-1-ureido )phenylacetamido] penicillanic acid).

18 18.4 (Theory 18.4 per- 8 MANUFACTURlNG INSTRUCTIONS The 100 mesh, sterile, pyrogen-free sodium 6-[D-a- I (3 -g'uanyl-l-u'reido)phenylacetamidolpenicillanate monohydrate is filled into sterile vials or disposabletype syringes. The product is reconstituted shortly before use by addition of the indicated amount of sterile, pyrogen-free water.

FORMULA Per Vial Crystalline, Sterile, pyrogen- 0.273 Gram free Sodium 6-[D-a-( S-guanyl- 1 -ureido)phenylacetamido]- penicillanate monohydrate, 100 mesh Amount of sterile, pyrogen-free q.s. 1.0 ml.

water required per vial This weight is the equivalent of 0.25 gram of anhydrous 6-[D-a-(3- guanyll -ureido)phenylacetamido lpenicillanic acid.

Potassium I 6-[D-a-(3-guan'yl-1-ureido)phe'nylacetamido}penicillanate dihydrate Solution for Parenteral Use MANUFACTURING INSTRUCTIONS The saltis filled into sterile vials or disposable-type syringes. The product is reconstituted shortly before use by addition of the indicated amount of sterile, pyrogen-free water.

to obtain 250 mgJml. of activity as the free-acid (zwitterion) This weight is equivalent to 0.25 gms. of anhydrous 6-[ D-a-( B-guanyl- 1-ureido)phenylacetamidolpenicillanic acid (called free acid" or zwitterion Large excesses of such basic salts as trisodium citrate, sodium ascorbate, .disodium phosphate and sodium acetate failed to solubilize 6-[D-a-(3-guanyl-1- ureiod)phenylacetamidolpenicillanic acid at a concentration greater than 50 mg./ml. in water. It was discovered, however, that trisodium phosphate and sodium-carbonate did solubilize 6-[D-a-(3-guanyl-1- ureido)phenylacetamidol-penicillanic acid in water at concentrations greater than 250 mgmJml. (pH 9.-9.4). The solutions showed stabilities similar to that of sodium ampicillin at the same concentrations. Dry-fill mixtures of 6[D-a(3-guany1-1-ureido)phenylacetamido] penicillanic acid (free acid," zwitterion) and sodium carbonate or trisodium phosphate are useful l.V. and I.M. dosage forms. Specific examples follow.

Solution for Parenteral Use of 6-[D-a-(3 -guanyl-lureido)-phenylacetamdio)penicillanic acid hemihydrate with Sodium. Carbonate (Dose: 250 mgJml.)

MANUFACTURING INSTRUCTIONS l. The sterile 200 mesh sodium carbonate and the sterile. 200 mesh crystalline 6-[D-a-(3-guanyllureido)phenylacetamido]penicillanic acid hemihydrate are mixed in a suitable sterile blender for I hour and then milled or screened to assure break up of any lumps.

2. The sterile'mixture above is filled into sterile vials or disposable-type syringes. The product is reconstituted shortly before use by addition of the indicated amount of sterile, pyrogen-free water.

FORMULA Per Vial Crystalline, 6-[Da-(3-'guanyll-ureido)phenylacetamido]- penicillanic acid hemihydrate (200 mesh), Sterile and Pyrogen Free Sodium Carbonate, (200 mesh), Sterile and Pyrogen Free Volume of Sterile, Pyrogen-Free Water required to obtain 250 mgm./ml.

0.25 grams 0.07 grams *The amount of Sodium Carbonate required may vary as to the minimum amount required to give a pH of 9.3-9.8 and/or a complete solution.

"The 250 mgJml. solution is stable within 10 percent for at least l hour at room temperature. This solution may be diluted to a 100 mgJml. solution which is stable within 10 percent for at least 2 hours at room temperature, or a 10 mg./ml. solution which is stable within 10 percent for at least 24 hours at room temperature. The 250 mgmJml. is equivalent to 250,000 units/ml.

Solution for Parenteral Use of 6-[D-a-(3-guanyl4- ureido)phenylacetamido]penicillanic acid hemihydrate with Trisodium Phosphate (Dose: 100 mg./ml.)

MANUFACTURING INSTRUCTIONS FORMULA Per Vial Crystalline 6-[D-tx-(3 guanyll-ureido)phenylacetamido]- 0.1 grams penicillanic acid hemihydrate, I00 mesh, sterile,

yrog'en-free risodium phosphate, I00 mesh, 0.04l grams sterile, pyrogen-free anhydrous Volume of water required to 0.9 ml." give I00 mgJml.

We claim:

I. Crystalline 6-[D-a-( 3-guanyI-l ureido)phenylacetamido]-penicillanic acid nitrate.

2. Crystalline 6-[D-a-(3-guanyl-l-ureido)phenylacetamido]-penicillanic acid nitrate r'nonohydrate.

3. The process of purifying impure, amorphous 6-[D- a-(3-guanyl-l-ureido )phenylacetamido lpenicillanic acid WIIICII COmPIIStBS mixing it with nitric acid in aqueous alcohol at a pH in the range of one to two, recovering the crystalline 6-[D-a-(3-guanyl-I-ureido)phenylacetamido1pehicillanic acid nitrate thus precipitated and then converting said nitrate to highly purified crystalline 6-[D-a-( 3-guanyl- I -ureido )-phenylacetamido1penicillanic acid by slurrying it in aqueous alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6-[Da-(3-guanyl-lureido)phenylacetamidolpenicillanic acid spontaneously soon precipitates and is then collected.

4. The process of claim 8 for purifying impure, amorphous 6-[ D-a-( 3-guanyI-l -ureido)phenylacetamido1penicillanic acid which comprises mixing it with nitric acid in percent (v/v) aqueous isopropyl alcohol at a pH in the range of 1.3 to 1.9, recovering the crystalline 6-[D-a-(3-guanyl-I-ureid0)phenylacetamido1penicillanic acid nitrate monohydrate thus precipitated and then converting said nitrate to highly purified crystalline 6-[D-a-(3-guanyI-I- ureido)phenylacetamido]penicillanic acid hemihydrate by slurrying it in 50 percent (v/v) aqueous isopropyl alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6:[D-a-(3- guanyl- 1-ureido)phenylacetamido]penicillanic acid hemihydrate spontaneously soon precipitates and is then collected. 

2. Crystalline 6-(D- Alpha -(3-guanyl-1-ureido)phenylacetamido)-penicillanic acid nitrate monohydrate.
 3. The process of purifying impure, amorphous 6-(D- Alpha -(3-guanyl-1-ureido)phenylacetamido)penicillanic acid which comprises mixing it with nitric acid in aqueous alcohol at a pH in the range of one to two, recovering the crystalline 6-(D- Alpha -(3-guanyl-1-ureido)phenyl-acetamido)penicillanic acid nitrate thus precipitated and then converting said nitrate to highly purified crystalline 6-(D- Alpha -(3-guanyl-1-ureido)-phenylacetamido)penicillanic acid by slurrying it in aqueous alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6-(D- Alpha -(3-guanyl-1-ureido)phenylacetamido)penicillanic acid spontaneously soon precipitates and is then collected.
 4. The process of claim 8 for purifying impure, amorphous 6-(D-Alpha -(3-guanyl-1-ureido)phenylacetamido)penicillanic acid which comprises mixing it with nitric acid in 90 percent (v/v) aqueous isopropyl alcohol at a pH in the range of 1.3 to 1.9, recovering the crystalline 6-(D- Alpha -(3-guanyl-1-ureido)phenylacetamido)penicillanic acid nitrate monohydrate thus precipitated and then converting said nitrate to highly purified crystalline 6-(D- Alpha -(3-guanyl-1-ureido)phenylacetamido)penicillanic acid hemihydrate by slurrying it in 50 percent (v/v) aqueous isopropyl alcohol and then adjusting the pH of said slurry with a base to the range of 4.5 to 6.0 to give a solution from which the purified crystalline 6-(D- Alpha -(3-guanyl- 1-ureido)phenylacetamido)penicillanic acid hemihydrate spontaneously soon precipitates and is then collected. 